#include <stdio.h>
#define PI 3.1415926535
int main() {
    float r = 5.0f;
    float circumference = 2 * PI * r;
    float area = PI * r * r;
    printf("圆的周长为：%.3f\n", circumference);
    printf("圆的面积为：%.3f\n", area);
    return 0;
}